For example, Japanese Unexamined Patent Application Publication No. 8-196950 (Patent Literature 1) and WO01/02099 (Patent Literature 2) disclose a spray gun, in which a gun barrel of the spray gun is provided with a coating material nozzle that ejects a coating material flow from a coating material ejection opening of a tip end portion thereof, and a air cap that surrounds the tip end portion of the coating material nozzle and defines in a gap with the tip end portion a ring shaped slit that ejects an air flow.
The tip end portion of the coating material nozzle is formed with a guide wall on a tip end surface thereof spreading from an opening edge of the coating material ejection opening toward a tip end side, and a plurality of V shaped air grooves on an outer peripheral surface thereof channeled from a predetermined position on a rear end side to the guide wall in a longitudinal direction. The guide wall is adapted to restrict the coating material flow ejected from the coating material ejection opening. The air grooves are adapted to guide a part of the air flow toward a front of the coating material ejection opening.
In the spray gun thus configured, when coating material is ejected from the coating material ejection opening to form the coating material flow, the air flow is introduced to the air grooves through the slit from a gun body to collide and mix with the coating material flow ejected from the coating material ejection opening while increasing in gas-liquid contact area. As a result thereof, it is possible, even if a low pressure air flow is employed, to effectively atomize the ejected coating material up to a central portion thereof.